/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/*
 *
 * Copyright (c) 2007 Dominik Spies <kontakt@dspies.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * Author: Dominik Spies <kontakt@dspies.de>
 *
 * This is a AutoIP implementation for the lwIP TCP/IP stack. It aims to conform
 * with RFC 3927.
 *
 *
 * Please coordinate changes and requests with Dominik Spies
 * <kontakt@dspies.de>
 */

/**
 * @file
 * AutoIP Automatic LinkLocal IP Configuration
 *
 */

/*******************************************************************************
 * USAGE:
 *
 * define LWIP_AUTOIP 1  in your lwipopts.h
 *
 * If you don't use tcpip.c (so, don't call, you don't call tcpip_init):
 * - First, call autoip_init().
 * - call autoip_tmr() all AUTOIP_TMR_INTERVAL msces,
 *   that should be defined in autoip.h.
 *   I recommend a value of 100. The value must divide 1000 with a remainder almost 0.
 *   Possible values are 1000, 500, 333, 250, 200, 166, 142, 125, 111, 100 ....
 *
 * Without DHCP:
 * - Call autoip_start() after netif_add().
 *
 * With DHCP:
 * - define LWIP_DHCP_AUTOIP_COOP 1 in your lwipopts.h.
 * - Configure your DHCP Client.
 *
 */

#include <net/lwip/opt.h>

#if LWIP_AUTOIP					/* don't build if not configured for use in lwipopts.h */

#include <net/lwip/mem.h>
#include <net/lwip/udp.h>
#include <net/lwip/ipv4/ip_addr.h>
#include <net/lwip/netif.h>
#include <net/lwip/ipv4/autoip.h>
#include <net/lwip/netif/etharp.h>

#include <stdlib.h>
#include <string.h>

/* 169.254.0.0 */
#define AUTOIP_NET         0xA9FE0000
/* 169.254.1.0 */
#define AUTOIP_RANGE_START (AUTOIP_NET | 0x0100)
/* 169.254.254.255 */
#define AUTOIP_RANGE_END   (AUTOIP_NET | 0xFEFF)

/** Pseudo random macro based on netif informations.
 * You could use "rand()" from the C Library if you define LWIP_AUTOIP_RAND in lwipopts.h */
#ifndef LWIP_AUTOIP_RAND
#define LWIP_AUTOIP_RAND(netif) ((((u32_t)((netif->hwaddr[5]) & 0xff) << 24) | \
								  ((u32_t)((netif->hwaddr[3]) & 0xff) << 16) | \
								  ((u32_t)((netif->hwaddr[2]) & 0xff) << 8) | \
								  ((u32_t)((netif->hwaddr[4]) & 0xff))) + \
								 (netif->autoip ? netif->autoip->tried_llipaddr : 0))
#endif							/* LWIP_AUTOIP_RAND */

/**
 * Macro that generates the initial IP address to be tried by AUTOIP.
 * If you want to override this, define it to something else in lwipopts.h.
 */
#ifndef LWIP_AUTOIP_CREATE_SEED_ADDR
#define LWIP_AUTOIP_CREATE_SEED_ADDR(netif) \
	htonl(AUTOIP_RANGE_START + ((u32_t)(((u8_t)(netif->hwaddr[4])) |	\
										((u32_t)((u8_t)(netif->hwaddr[5]))) << 8)))
#endif							/* LWIP_AUTOIP_CREATE_SEED_ADDR */

/* static functions */
static void autoip_handle_arp_conflict(struct netif *netif);

/* creates a pseudo random LL IP-Address for a network interface */
static void autoip_create_addr(struct netif *netif, ip_addr_t *ipaddr);

/* sends an ARP probe */
static err_t autoip_arp_probe(struct netif *netif);

/* sends an ARP announce */
static err_t autoip_arp_announce(struct netif *netif);

/* configure interface for use with current LL IP-Address */
static err_t autoip_bind(struct netif *netif);

/* start sending probes for llipaddr */
static void autoip_start_probing(struct netif *netif);

/** Set a statically allocated struct autoip to work with.
 * Using this prevents autoip_start to allocate it using mem_malloc.
 *
 * @param netif the netif for which to set the struct autoip
 * @param dhcp (uninitialised) dhcp struct allocated by the application
 */
void autoip_set_struct(struct netif *netif, struct autoip *autoip)
{
	LWIP_ASSERT("netif != NULL", netif != NULL);
	LWIP_ASSERT("autoip != NULL", autoip != NULL);
	LWIP_ASSERT("netif already has a struct autoip set", netif->autoip == NULL);

	/* clear data structure */
	memset(autoip, 0, sizeof(struct autoip));
	/* autoip->state = AUTOIP_STATE_OFF; */
	netif->autoip = autoip;
}

/** Restart AutoIP client and check the next address (conflict detected)
 *
 * @param netif The netif under AutoIP control
 */
static void autoip_restart(struct netif *netif)
{
	netif->autoip->tried_llipaddr++;
	autoip_start(netif);
}

/**
 * Handle a IP address conflict after an ARP conflict detection
 */
static void autoip_handle_arp_conflict(struct netif *netif)
{
	/* Somehow detect if we are defending or retreating */
	unsigned char defend = 1;	/* tbd */

	if (defend) {
		if (netif->autoip->lastconflict > 0) {
			/* retreat, there was a conflicting ARP in the last
			 * DEFEND_INTERVAL seconds
			 */
			LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("autoip_handle_arp_conflict(): we are defending, but in DEFEND_INTERVAL, retreating\n"));

			/* TODO: close all TCP sessions */
			autoip_restart(netif);
		} else {
			LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("autoip_handle_arp_conflict(): we are defend, send ARP Announce\n"));
			autoip_arp_announce(netif);
			netif->autoip->lastconflict = DEFEND_INTERVAL * AUTOIP_TICKS_PER_SECOND;
		}
	} else {
		LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("autoip_handle_arp_conflict(): we do not defend, retreating\n"));
		/* TODO: close all TCP sessions */
		autoip_restart(netif);
	}
}

/**
 * Create an IP-Address out of range 169.254.1.0 to 169.254.254.255
 *
 * @param netif network interface on which create the IP-Address
 * @param ipaddr ip address to initialize
 */
static void autoip_create_addr(struct netif *netif, ip_addr_t *ipaddr)
{
	/* Here we create an IP-Address out of range 169.254.1.0 to 169.254.254.255
	 * compliant to RFC 3927 Section 2.1
	 * We have 254 * 256 possibilities */

	u32_t addr = ntohl(LWIP_AUTOIP_CREATE_SEED_ADDR(netif));
	addr += netif->autoip->tried_llipaddr;
	addr = AUTOIP_NET | (addr & 0xffff);
	/* Now, 169.254.0.0 <= addr <= 169.254.255.255 */

	if (addr < AUTOIP_RANGE_START) {
		addr += AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;
	}
	if (addr > AUTOIP_RANGE_END) {
		addr -= AUTOIP_RANGE_END - AUTOIP_RANGE_START + 1;
	}
	LWIP_ASSERT("AUTOIP address not in range", (addr >= AUTOIP_RANGE_START) && (addr <= AUTOIP_RANGE_END));
	ip4_addr_set_u32(ipaddr, htonl(addr));

	LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("autoip_create_addr(): tried_llipaddr=%" U16_F ", %" U16_F ".%" U16_F ".%" U16_F ".%" U16_F "\n", (u16_t)(netif->autoip->tried_llipaddr), ip4_addr1_16(ipaddr), ip4_addr2_16(ipaddr), ip4_addr3_16(ipaddr), ip4_addr4_16(ipaddr)));
}

/**
 * Sends an ARP probe from a network interface
 *
 * @param netif network interface used to send the probe
 */
static err_t autoip_arp_probe(struct netif *netif)
{
	return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast, (struct eth_addr *)netif->hwaddr, IP_ADDR_ANY, &ethzero, &netif->autoip->llipaddr, ARP_REQUEST);
}

/**
 * Sends an ARP announce from a network interface
 *
 * @param netif network interface used to send the announce
 */
static err_t autoip_arp_announce(struct netif *netif)
{
	return etharp_raw(netif, (struct eth_addr *)netif->hwaddr, &ethbroadcast, (struct eth_addr *)netif->hwaddr, &netif->autoip->llipaddr, &ethzero, &netif->autoip->llipaddr, ARP_REQUEST);
}

/**
 * Configure interface for use with current LL IP-Address
 *
 * @param netif network interface to configure with current LL IP-Address
 */
static err_t autoip_bind(struct netif *netif)
{
	struct autoip *autoip = netif->autoip;
	ip_addr_t sn_mask, gw_addr;

	LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_bind(netif=%p) %c%c%" U16_F " %" U16_F ".%" U16_F ".%" U16_F ".%" U16_F "\n", (void *)netif, netif->name[0], netif->name[1], (u16_t)netif->num, ip4_addr1_16(&autoip->llipaddr), ip4_addr2_16(&autoip->llipaddr), ip4_addr3_16(&autoip->llipaddr), ip4_addr4_16(&autoip->llipaddr)));

	IP4_ADDR(&sn_mask, 255, 255, 0, 0);
	IP4_ADDR(&gw_addr, 0, 0, 0, 0);

	netif_set_ipaddr(netif, &autoip->llipaddr);
	netif_set_netmask(netif, &sn_mask);
	netif_set_gw(netif, &gw_addr);

	/* bring the interface up */
	netif_set_up(netif);

	return ERR_OK;
}

/**
 * Start AutoIP client
 *
 * @param netif network interface on which start the AutoIP client
 */
err_t autoip_start(struct netif *netif)
{
	struct autoip *autoip = netif->autoip;
	err_t result = ERR_OK;

	if (netif_is_up(netif)) {
		netif_set_down(netif);
	}

	/* Set IP-Address, Netmask and Gateway to 0 to make sure that
	 * ARP Packets are formed correctly
	 */
	ip_addr_set_zero(&netif->ip_addr);
	ip_addr_set_zero(&netif->netmask);
	ip_addr_set_zero(&netif->gw);

	LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("autoip_start(netif=%p) %c%c%" U16_F "\n", (void *)netif, netif->name[0], netif->name[1], (u16_t)netif->num));
	if (autoip == NULL) {
		/* no AutoIP client attached yet? */
		LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_start(): starting new AUTOIP client\n"));
		autoip = (struct autoip *)mem_malloc(sizeof(struct autoip));
		if (autoip == NULL) {
			LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_start(): could not allocate autoip\n"));
			return ERR_MEM;
		}
		memset(autoip, 0, sizeof(struct autoip));
		/* store this AutoIP client in the netif */
		netif->autoip = autoip;
		LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_start(): allocated autoip"));
	} else {
		autoip->state = AUTOIP_STATE_OFF;
		autoip->ttw = 0;
		autoip->sent_num = 0;
		ip_addr_set_zero(&autoip->llipaddr);
		autoip->lastconflict = 0;
	}

	autoip_create_addr(netif, &(autoip->llipaddr));
	autoip_start_probing(netif);

	return result;
}

static void autoip_start_probing(struct netif *netif)
{
	struct autoip *autoip = netif->autoip;

	autoip->state = AUTOIP_STATE_PROBING;
	autoip->sent_num = 0;
	LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("autoip_start_probing(): changing state to PROBING: %" U16_F ".%" U16_F ".%" U16_F ".%" U16_F "\n", ip4_addr1_16(&netif->autoip->llipaddr), ip4_addr2_16(&netif->autoip->llipaddr), ip4_addr3_16(&netif->autoip->llipaddr), ip4_addr4_16(&netif->autoip->llipaddr)));

	/* time to wait to first probe, this is randomly
	 * choosen out of 0 to PROBE_WAIT seconds.
	 * compliant to RFC 3927 Section 2.2.1
	 */
	autoip->ttw = (u16_t)(LWIP_AUTOIP_RAND(netif) % (PROBE_WAIT * AUTOIP_TICKS_PER_SECOND));

	/*
	 * if we tried more then MAX_CONFLICTS we must limit our rate for
	 * accquiring and probing address
	 * compliant to RFC 3927 Section 2.2.1
	 */
	if (autoip->tried_llipaddr > MAX_CONFLICTS) {
		autoip->ttw = RATE_LIMIT_INTERVAL * AUTOIP_TICKS_PER_SECOND;
	}
}

/**
 * Handle a possible change in the network configuration.
 *
 * If there is an AutoIP address configured, take the interface down
 * and begin probing with the same address.
 */
void autoip_network_changed(struct netif *netif)
{
	if (netif->autoip && netif->autoip->state != AUTOIP_STATE_OFF) {
		netif_set_down(netif);
		autoip_start_probing(netif);
	}
}

/**
 * Stop AutoIP client
 *
 * @param netif network interface on which stop the AutoIP client
 */
err_t autoip_stop(struct netif *netif)
{
	netif->autoip->state = AUTOIP_STATE_OFF;
	netif_set_down(netif);
	return ERR_OK;
}

/**
 * Has to be called in loop every AUTOIP_TMR_INTERVAL milliseconds
 */
void autoip_tmr()
{
	struct netif *netif = netif_list;
	/* loop through netif's */
	while (netif != NULL) {
		/* only act on AutoIP configured interfaces */
		if (netif->autoip != NULL) {
			if (netif->autoip->lastconflict > 0) {
				netif->autoip->lastconflict--;
			}

			LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_tmr() AutoIP-State: %" U16_F ", ttw=%" U16_F "\n", (u16_t)(netif->autoip->state), netif->autoip->ttw));

			switch (netif->autoip->state) {
			case AUTOIP_STATE_PROBING:
				if (netif->autoip->ttw > 0) {
					netif->autoip->ttw--;
				} else {
					if (netif->autoip->sent_num >= PROBE_NUM) {
						netif->autoip->state = AUTOIP_STATE_ANNOUNCING;
						netif->autoip->sent_num = 0;
						netif->autoip->ttw = ANNOUNCE_WAIT * AUTOIP_TICKS_PER_SECOND;
						LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("autoip_tmr(): changing state to ANNOUNCING: %" U16_F ".%" U16_F ".%" U16_F ".%" U16_F "\n", ip4_addr1_16(&netif->autoip->llipaddr), ip4_addr2_16(&netif->autoip->llipaddr), ip4_addr3_16(&netif->autoip->llipaddr), ip4_addr4_16(&netif->autoip->llipaddr)));
					} else {
						autoip_arp_probe(netif);
						LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_tmr() PROBING Sent Probe\n"));
						netif->autoip->sent_num++;
						/* calculate time to wait to next probe */
						netif->autoip->ttw = (u16_t)((LWIP_AUTOIP_RAND(netif) % ((PROBE_MAX - PROBE_MIN) * AUTOIP_TICKS_PER_SECOND)) + PROBE_MIN * AUTOIP_TICKS_PER_SECOND);
					}
				}
				break;

			case AUTOIP_STATE_ANNOUNCING:
				if (netif->autoip->ttw > 0) {
					netif->autoip->ttw--;
				} else {
					if (netif->autoip->sent_num == 0) {
						/* We are here the first time, so we waited ANNOUNCE_WAIT seconds
						 * Now we can bind to an IP address and use it.
						 *
						 * autoip_bind calls netif_set_up. This triggers a gratuitous ARP
						 * which counts as an announcement.
						 */
						autoip_bind(netif);
					} else {
						autoip_arp_announce(netif);
						LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_tmr() ANNOUNCING Sent Announce\n"));
					}
					netif->autoip->ttw = ANNOUNCE_INTERVAL * AUTOIP_TICKS_PER_SECOND;
					netif->autoip->sent_num++;

					if (netif->autoip->sent_num >= ANNOUNCE_NUM) {
						netif->autoip->state = AUTOIP_STATE_BOUND;
						netif->autoip->sent_num = 0;
						netif->autoip->ttw = 0;
						LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE, ("autoip_tmr(): changing state to BOUND: %" U16_F ".%" U16_F ".%" U16_F ".%" U16_F "\n", ip4_addr1_16(&netif->autoip->llipaddr), ip4_addr2_16(&netif->autoip->llipaddr), ip4_addr3_16(&netif->autoip->llipaddr), ip4_addr4_16(&netif->autoip->llipaddr)));
					}
				}
				break;
			}
		}
		/* proceed to next network interface */
		netif = netif->next;
	}
}

/**
 * Handles every incoming ARP Packet, called by etharp_arp_input.
 *
 * @param netif network interface to use for autoip processing
 * @param hdr Incoming ARP packet
 */
void autoip_arp_reply(struct netif *netif, struct etharp_hdr *hdr)
{
	LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE, ("autoip_arp_reply()\n"));
	if ((netif->autoip != NULL) && (netif->autoip->state != AUTOIP_STATE_OFF)) {
		/* when ip.src == llipaddr && hw.src != netif->hwaddr
		 *
		 * when probing  ip.dst == llipaddr && hw.src != netif->hwaddr
		 * we have a conflict and must solve it
		 */
		ip_addr_t sipaddr, dipaddr;
		struct eth_addr netifaddr;
		ETHADDR16_COPY(netifaddr.addr, netif->hwaddr);

		/* Copy struct ip_addr2 to aligned ip_addr, to support compilers without
		 * structure packing (not using structure copy which breaks strict-aliasing rules).
		 */
		IPADDR2_COPY(&sipaddr, &hdr->sipaddr);
		IPADDR2_COPY(&dipaddr, &hdr->dipaddr);

		if ((netif->autoip->state == AUTOIP_STATE_PROBING) || ((netif->autoip->state == AUTOIP_STATE_ANNOUNCING) && (netif->autoip->sent_num == 0))) {
			/* RFC 3927 Section 2.2.1:
			 * from beginning to after ANNOUNCE_WAIT
			 * seconds we have a conflict if
			 * ip.src == llipaddr OR
			 * ip.dst == llipaddr && hw.src != own hwaddr
			 */
			if ((ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr)) || (ip_addr_cmp(&dipaddr, &netif->autoip->llipaddr) && !eth_addr_cmp(&netifaddr, &hdr->shwaddr))) {
				LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING, ("autoip_arp_reply(): Probe Conflict detected\n"));
				autoip_restart(netif);
			}
		} else {
			/* RFC 3927 Section 2.5:
			 * in any state we have a conflict if
			 * ip.src == llipaddr && hw.src != own hwaddr
			 */
			if (ip_addr_cmp(&sipaddr, &netif->autoip->llipaddr) && !eth_addr_cmp(&netifaddr, &hdr->shwaddr)) {
				LWIP_DEBUGF(AUTOIP_DEBUG | LWIP_DBG_TRACE | LWIP_DBG_STATE | LWIP_DBG_LEVEL_WARNING, ("autoip_arp_reply(): Conflicting ARP-Packet detected\n"));
				autoip_handle_arp_conflict(netif);
			}
		}
	}
}

#endif							/* LWIP_AUTOIP */
